How It Works
To a pollster, less is more
WASHINGTON (CNN) -- Despite the plethora of public opinion polls coming out this election year, few Americans ever answer questions from a pollster. CNN polling director Keating Holland explains why in this week's "How It Works."
"A metaphor that pollsters frequently use is a chef in the kitchen," Holland said. "If he wants to see whether a soup needs more salt, he doesn't need to drink all of the soup. He only needs to stir the pot around and taste a spoonful of it."
The same principle holds true for polls. As long as the survey group is a true statistical representation of the country -- in terms of race and gender, for example -- even a small pool of respondents can yield results that are accurate for the whole country.
And that pool of respondents is quite small. After all, there are more than 200 million adults in the United States, but as few as 1,000 are called on any given poll.
It's all computerized, Holland said.
"We pick the area code, the computer generates the seven digits," he said. "That means that everyone in America has an equal chance of being selected. That in turn means that a sample of a thousand people can represent 200 million."
Holland said it all comes down to telephone numbers.
"We're not picking people based on what they know, or how they are planning to vote, or any other factor," he said. "We don't know anything about them. All we know is their telephone number, and that's it."
But once pollsters get information about those polled, they do statistical calculations to make sure the group's demographics accurately reflect the American public in terms of race, age, education and other factors.
CNN's Jennifer Mikell and Mark Rodeffer contributed to this report.